Ceramic mold



April 11,1944. J. R. THOMPSON CERAMI C MOLD Original Filed Oct. 2, 1940 3maentor Jsz /x A. Z/OMP so.

Patented Apr. 11, 1944 UNITED STATES zsiatze TENT orrlcr.

CERAMIC MOLD Original application October 2, 1940, Serial No.

Divided and this application December 26, 1940, Serial No. 371,721

8 Claims.

The present invention relates to an improved ceramic mold especially adapted for the production of vitreous or semi-vitreous chinaware, and

particularly for chinaware of the bowl type in which a bowl is fashioned with a foot or exterior hollow base and with exterior handles, the base and handles being integral with the bowl to form an integral vessel.

The invention set forth in this application for patent is a division of the subject matter of my co-pending application, Serial Number 359,- 426, filed October 2', 1940.

In carrying out the present invention I employ a two-piece mold having a removable core, and the mold is fashioned with a matrix into which clay slip is poured to form the bowl-body and exterior handles after which casting operation the integral foot or hollow base of the bowl is fashioned as an integral part of the bowl during a rotary movement imparted to the mold while the slip is being supplied thereto.

As is well known in the ceramic art, the liquid clay or slip employed is a homogeneous, freely flowing, creamy mixture of finely divided clay and other ingredients. The various parts of the mold or matrix, into which the slip is poured, are made up of plaster of Paris, or other porous and absorbent material which will absorb the moisture from the slip or clay mixture. After the deposited material has set in the matrix,

the mold is removed from its base, and then separable portions of the mold are separated to permit the green bowl to season preparatory to subsequent steps of finishing, glazing, decorating, and. otherwise completing the bowl for commercial purposes.

The mold, which as a whole is divided from and mounted on a one-piece horizontal base, includes a cope or upper removable portion that is divided vertically into two sections, and a core that is removable and separable from both the base and the cope, and the concavo-convex vessel is fashioned in inverted or upside down position within the matrix. The horizontal and vertical divisions, and the separable parts of the mold, facilitate the assembling of the mold as well as the removal of the green bowl after casting. Some accessories (not herein shown) are or may be employed in mounting the mold upon a rotary head or jigger spindle in usual manner so that casting may be accomplished under centrifugal force as the mold is rotated.

The invention consists in certain novel combinations and arrangements of structures in the and claimed. In the accompanying drawing I have illustrated one complete example of the physical embodiment of my invention in which the parts are combined and arranged in accord with one mode I have thus far devised for the practical application of the principles of my invention. It will be understood however that changes and alterations maybe made in these exemplifying drawing within the scope of my appended claims without departing from the principles of my invention.

Figure 1 is a top plan view of a mold embodying my invention with interior parts shown by dotted lines.

Figure 2 is a sectional view at line 2-2 of Figure 1 which is the dividing line between the two cope sections.

Figure 3 is a side view of an upright bowl of the type produced in the mold, showing exterior handles, lugs, and the hollow base integral with the body of the bowl.

It will be understood that the matrix of the mold may be formed or shaped to produce various forms or shapes of concavo-convex vessels, but for convenience of illustration and description I have illustrated the mold with a matrix adapted to produce the somewhat hemispherical mold as shown in Figure 3. This bowl B has a hollow annular flange or circular base F, and exterior, diametrically alined handles or ribs H that terminate in end lugs L. Slots or spaces S, S, are provided in the handles or ribs H, and the numeral 23 indicates by dotted lines the hollow structure of the base or foot of the bowl. The body, base or foot, handles, and lugs, are all cast integral within the mold so that no marks appear to indicate junctions of parts, and the inherent strength of the material permeates all parts of the bowl.

In Figure 1 dotted lines are employed to indicate the circular parts of the mold and matrix, the handles, and the lugs, and in Figure 2 the upper mold-member or cope is shown as horizontally divided from the one-piece base, and the cope itself is shown as vertically divided into two sections.

In Figure 2 the mold is shown as including a base section 1, here shown as rectangular in shape and fashioned of suitable material, and the upper face of the base is provided with a circular recess or depression 2, of suitable depth. A centering ring or continuous rib 3 is fashioned on the upper face 4 of the base i, and. a hollow dome-shaped core 5, with tapering lower edge,

mold as will hereinafter be more fully set forth .55 is mounted in the recess or depression of the base. This removable o1 separable core is fashioned with a mold-face 6 that corresponds to the contour of the interior face of the body of the bowl, and the body of the bowl, in inverted position is built upon the core to conform to the outer face 6 of the core.

A centrally located vent hole I in the core is closed by a tapered plug 8 while the molding or casting operations are progressing, and the domeshaped core is fashioned with an exterior annular shoulder 9, above its tapered edge, to rest upon a complementary shoulder surrounding the recess 2, to assist in properly centering the core within the rib 3.

The centering ring or rib 3 surrounds the core and its mold-face 6, and the flat horizontal face of the ring or rib 3 is fashioned with predetermined Width to determine the thickness of the body-wall of the bowl and to produce the annular or circular edge of thebowl.

To facilitate handling of the dome-shaped core it may be fashioned with diametrically alined interior sockets |0,||l into which the ends of a stick or handle bar II are inserted, as indicated in Figure 1 by dotted lines.

It will be noted that the recessed base I and the dome-shaped hollow core 5 are each a unitary, one-piece structure, and they form the drag portion of the mold. The cope or upper portion of the mold however, is composed of two separable sections I2 and I3 that are vertically divided and rest on the base I.

The sections I2 and I3 may be rigidly held together in suitable manner, as by the use of sockets I4 and dowel pins I5, and this separable cope member may be clamped in suitable manner on the face 4 of the base I so that when the clamp is released the cope may be removed with a cavity and together these two cavities form a somewhat hemi-spherical mold-cavity with a mold-face I6 that is spaced from the complementary mold-face 6 of the core 5 to provide the thickness of the wall of the body of the bowl. This space between the two molding faces 6 and I6 forms the matrix for the body of the bowl into which the slip is poured or deposited for the formation of the concavo-convex vessel.

To form the handles H on the exterior of the body B of the bowl each cope-section l2 and I3 is fashioned with'a half-groove I i and I8 as indicated by dotted lines in Figure 1. These complementary pairs of half-grooves form the pair of radially or diametrically extending grooves that produce the two ribs or handles of the bowl. These grooves I! and I8 at their outer ends terminate in recesses I9 and also formed in halves in the abutting faces of the cope-sections I2 and I3, and these recesses I9 and 20 provide for the lugs L, L of the bowl-handles.

The clay slip is deposited in the concavoconvex matrix preferably through gates or pouring passages 2|, 2|, located at opposite sides of the center of the matrix, and these passages are formed by the use of two complementary vertically extending grooves in the abutting faces of the cope-sections I2 and I3. If desired a suitable funnel or nozzle may be employed for discharging the slip into each of these passages 2|, 2|. As indicated, the large passages terminate at their lower ends in forked sprue-holes 22 and 23, the sprue-holes 22 opening into the matrix handles, and lugs of the inverted bowl.

through the grooves I7 and I8, and the sprueholes 23 opening into the recesses I9 and 23 to insure proper distribution of the fluid clay. These pouring passages, ducts, or holes are formed, onehalf in each of the abutting faces of the copesections I2 and I3; and abutting half-lugs 2-2, 24 are also provided in these faces and located in the adjoining handle grooves of the copesections. These abutting half-lugs 24, 26, form two cross bridges in the handle grooves, and these bridges are instrumental in the formation of the spaces or slots S, S between the body B and the handle H of the bowl.

In the top center of the removable and separable two-piece cope or upper mold member is fashioned a funnel shaped mold cavity 25, having an annular groove 26, and a neck portion 21, the neck portion as shown in Figure 2 opening into and merging with the matrix for the body of the bowl. This mold cavity made up-of com plementary halves in the abutting faces of the cope sections and including the annular groove and neck, is instrumental in the formation of the hollow supporting base or annular flange F of the bowl, and the numeral 28 in Figure 3 indicates by dotted lines the hollow formation of the base, while in Figure 2 the dotted line indicates what will be the thickness of the bottom portion of the bowl.

As before stated, the body of the bowl or other hollow ceramic vessel, with its exterior handles and lugs integral with the body, is fashioned within the matrix by pouring the fluid clay or I slip through the passages 2|, 2| at opposite sides of the center of the matrix. The sprue-holes 22 and 23 of the passages 2|, 2| distribute the slip so that the lug-recesses I9 and 20 and that portion of the matrix directly over the centering ring 3 are first filled with the plastic mixture. As the matrix is gradually filled with the slip, air vented from the matrix throughthe central moldingcavity 25 permits the formation of solid walls, As the lowermost portion of the matrix becomes filled with the fluid clay, the body of the bowl is gradually built up, as are also the handles and lugs, and the body-wall of the bowl is formed between the molding surfaces 6 and I 6 of the matrix.

By varying the width of the upper face of the centering ring 3 and the corresponding width of the space forming the matrix, it will be apparent that the thickness of the wall of the bowl may be predetermined.

In its inverted position the body of the bowl is built up to a desired height by this step of casting the bowl on the core and this desired height may be up to the junction of the neck 21 with the matrix, leaving open that portion which subsequently becomes the bottom of the bowl.

This unfinished bottom portion indicated by dotted lines 28 in Figures 2 and 3, and the hollow supporting base F'of the bowl in Figure 3, are fashioned by the step of open-casting during which step of open-casting, the slip is poured into the molding cavity 25 at the top center of the mold, while the mold is revolving on a rotary head or jigger-spindle in well known manner, This open-casting step follows immediately after the pouring of the slip into the two passages 2|, 2|, the supply of slip being transferred from passages 2|, 2|, to the molding cavity 25, and therefore the annular, hollow supporting baseof the bowl is fashioned as an integral and. intact portion of the bowl.

As the slip is poured into the funnel shaped molding cavity 25 this cavity becomes the rotary former for the hollow supporting base or annular flange F of the bowl and the bottom of the bowl and thickness of the base wall are built up to the desired thickness.

As the slip is poured into the molding cavity 25, the material is thrown by centrifugal force into the annular groove 26, and against the annular surface of the neck 21 to'form the hollow base integral with the body of the bowl. The wall of the hollow supporting base follows the general outline of the casting cavity or molding cavity 25, the inside of the cavity of course forming the outside of the supporting base.

The moisture from the slip, both with respect to the body of the bowl and the supporting base of the bowl as well as the handles and lugs of the bowl, penetrates into the surrounding porous, absorbent mold members, leaving the green body wall of the bowl adhering to the core 5, and the supporting base wall F or base adheres to the wall of the molding cavity. The transfer of moisture from the cast piece, due either to capillary attraction or to centrifugal force, dries the cast article to a certain degree.

The green bowl is permitted to stand in its mold for a period of time sufficient for the plastic material to set and attain the proper condition to permit removal of the mold. separable cope-sections l2 and i3 may first be removed from their enclosing positions exterior of the inverted bowl, The core 5 with the cast bowl mounted thereon may then be lifted from the base i and the green bowl is permitted to season for a suitable period of time before firing.

As the slip dries it shrinks upon and adheres to the mold parts, and due to suction, or to atmospheric pressure the interior surface of the green bowl remains in close contact with the molding face 6 of the core, This vacuum condition created over the core prevents facile removal of the core. After the base has been separated from the core and the position of the mold has been reversed from the position of Figure 2; to release the adhering parts one from another without marring the cast bowl a gentle tapping on the smaller end of the tapered. plug 8 releases the plug, vents the lower part of the mold over the core, and breaks this close contact thereby permitting admission of air between the bowl and the core.

Thus by the use of my mold, ceramic vessels such as casseroles, cups, sauce boats, sugar bowls,

creamers and similar concavo-convex chinaware rial is employed or enters into the structure of the vessel, only the predetermined quantity of slip being used to insure the desired form, shape, and size of the bowl and its parts.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a ceramic mold adapted to produce an inverted bowl having an integral exterior hollow supporting base, the combination with a mold base and a removable core having a convex If desired, the 3 molding face, of a vertically divided cope member mounted on the mold base and having a concave molding face, said cope member at its 'dividing line having an upper open-top castingcavity open at its bottom to the matrix formed between the molding faces, whereby the bowl may be cast with its bottom portion forming the top portion of the hollow supporting base.

2. In a ceramic mold adapted to produce an inverted vessel having an exterior hollow opposed supporting base, the combination with a mold base and a removable core having a convex face, of a cope member having a concave face, and said cope member having an open-top castingcavity merging at its bottom with the upper portion of the matrix formed by said faces, whereby the vessel may be cast with its bottom portion forming the top portion of the integral supporting-base.

3. In a ceramic mold adapted to produce an inverted bowl having an integral exterior hollow supporting base, the combination with a mold base and a removable hollow core having a convex face, of a vertically divided cope having a concave face and mounted on the mold base, said cope at its dividing line having an upper opentop casting-cavity conforming to the exterior of the supporting-base and merging at its lower part with the upper part of the matrix formed by said faces.

4. In a ceramic mold adapted to produce an inverted bowl having an integral exterior hollow supporting base, the combination with a mold base and a core having a convex face, of a cope having a concave face and mounted on the moldbase, said cope having an upper open-top casting cavity conforming to the exterior of the supporting base and merging at its lower part with the upper part of the matrix formed between said faces, and said cope also having a pouring passage extending below said cavity and communicating with the lower peripheral part of the matrix.

5. In a ceramic mold adapted to produce an inverted bowl having an integral exterior hollow supporting base, the combination with a mold base, and a removable core having an exterior convex face and mounted on the mold-base, of a cope having a concave face and mounted on the mold-base, said core having an upper open top casting cavity merging at its bottom with the matrix formed between said faces, and venting means mounted in the core and accessible after the mold and core have been separated from the mold-base to facilitate removal of the core from the cast piece.

6. In a, ceramic mold adapted to produce an inverted bowl having an integral exterior hollow supporting base, the combination with a mold-base and a hollow dome-shaped core mounted on the mold base, of a vertically divided cope having a concave face and mounted on the mold-base, said cope at its dividing line having an upper open-top casting-cavity merging at its bottom with the upper portion of the matrix formed by said faces, and venting means mounted in and accessible from within the hollow core after the mold base and core have been separated to facilitate removal of the core from the cast piece.

'7. In a ceramic mold adapted to produce an inverted bowl having an integral exterior hollow supporting-base, the combination with a mold base, and a hollow dome-shaped removable core having an exterior molding face and mounted on the mold-base, of a' cope having a complementary molding face and mounted on the moldbase, said cope member having an upper opentop casting cavity merging at its bottom with the upper part of the matrix formed between said faces, said core having a vent communicating with the matrix, and a removable plug in said vent accessible from within the hollow core after the core has been separated from the mold-base to facilitate removal of the core from the bowl.

8. In a ceramic mold adapted to produce an inverted bowl, the combination with a mold-base,

- of a hollow dome-shaped core having a convex molding face, a cope having a concave molding face, and means for casting a bowl in the matrix between said faces, said core having a vent communicating with the matrix, and a removable plug in said vent accessible from within the core after the latter has been separated from the mold-base.

JOSEPH R. THOMPSON. 

